Process for separating hydrocarbons



- C. B. WATSON IRQCBSS' FUR SEPARATING HYDROCARBONS Fi'led Dec. 26, 1925 Attorney.

Patented June 19, 1928 UNITED STATES PATENT OFFICE.

CORNELIUS IB. WATSON, OF COLUMBUS, OHIO, ASSIGNOR TO THE PURE OIL COMPANY, OF CHICAGO,.ILI|IN .OIS, A CORPORATION OF OHIO.

PROCESS FOR SEPARATING HYDROCARBONS.

Application filed December 26, 1925. Serial No. 77,784.

This invention relates to an improved process for treating the heavy residuum products discharged from petroleum cracking stills, distilling and fractionating apparafi tus, t the end of raising their economic value and to utilize the same more advantageously than has hitherto been considered practicable.

Another object of theinvention is the prono vision of a process of this character by which is recovered the lighter fractions contained in the residuum, and at the same time to make possible the convenient and eco nomic consumption of the remaining heavier 5. fractions, which may be in the form of heavy oil, containing oil and carbon, free carbon, coke, asphalt or tar either singly or in combination.

Ordinarily in petroleum cracking processes the oil is initially forced through heated coils in which the oil is heated to the required temperature and is'then lead toa vessel wherein is separated lighter oil fractions from the heavier. The heavier oil, or oil and carbon, free carbon, coke, asphalt or tar, which remains in the vessel after the more volatile fractions have passed off, is removed from the bottom of the vessel, and is suitably cooled and collected. This residiuum is very thick and heavy, and contains not only a quantity of more valuable lighter oil fractions, which have not been vaporized in the Vessel but also may contain the above specified carbon, coke or tar content, which makes the residuum very difficult to handle, necessitating ordinarily the subjecting of the same to high temperatures.

When the residuum cools it tends in certain oils to solidify, is difficult and expensive to remove from the storage tanks or receptacles, and even in cases where it is heated the carbon, coke or tar content thereof has a tendency to obstruct the lines 01 apparatus in which it is being handled.

By the provision of the present invention an improved process is provided for treating the residuum products to the end that the same may have the lighter and more valuable products effectively extracted therefrom, and to provide a treatment for the remaining and thicker products so that the latter may be usefully employed for fuel purposes in the operation of still burners or in other desired capacities.

Figure 3 is a vertical sectional view of.

the supplemental still,

Figure 4 is a detail view of a modified form of the invention.

In accordanc with the present invention oil to be cracked, fractionated or distilled may be pumped under pressure by means of a pump 1 through a pipe line 1, leading from any suitable source of supply to a furnace 2 which, in the present instance, is shown as being equipped with the ordinary heating tube coils 3. The -oil is forced through these tubes, where it is heated to the required temperature, and then passes through a pipe line into a vessel 5. In this vessel the lighter oil fractions rise to the top and are taken off through a vapor pipe line 6, which leads the vapors to a condenser (not shown), where the vapors may be lead to fractionating apparatus or may b condensed and then subjected to suitable further treatment. The oil or oil and carbon residuum remains in the vessel 5 until it is allowed to run out at or near the bottom through a pipe line 7, and, in accordance with previous practice, is passed from the line 7 through a cooling pipe coil 8, which is ordinarily located in the water filled casing 9, and then through a pipe line 10 into a collection tank 11.

This residuum is very heavy and contains not only a quantity of valuable lighter oil fractions which fail to vaporize in the vessel 5, but also a quantity of oil, oil and carbon, asphalt, coke or tar which makes the oil very diflicult to handle through pumps and pipe tures.- As previously stated this thick re siduuin has atendency to clog the pipe lines and apparatus through which it is passed or collected and in the past the disposal and handling thereof has been a great problem in petroleum refining plants.

In accordance this difficulty has been overcome by connecting the bottom of the vessel 5 with a pipe line 12, provided with a control valve 12 through which the oil is passed without with the present invention being cooled into a still 13. A steam or other gas et-19 is introduced into the pipe line 12 for the purpose of preventing the line 12 from clogging. and, to cause hot residuum to enter the still 13 with a blast or blowing effect, and to aid in the atomization or vaporization'of the remaining lighter oil fractions. The still 13 in this instance is equipped with a perforated steam or other gas coil 14 arranged close to the bottom of the still. The steam or other gas going out of the perforations in the coil tends to keep the oil in the still agitated, preventing the setting out of carbon, coke or tar and at the same time helping to atomize or vaporize the lighter oil fractions contained in the residuum.

The still 13 is efficiently insulated to prevent loss of heat by radiation and to keep the temperature of the oil as high as possible. Preferably, said still is operated at or about atmospheric pressure. The hot oil and carbon or coke and tar and other similar content is drawn out of the bottom of the still 13 through the insulated pipe line 15, by a pump 16, and is circulated continuously at high velocityand pressure through the insulated belt supply pipe line which connects to points of fuel oil consumption in the refinery, and the surplus is then returned to the still 13 through the nozzle 25 arranged in the still near the bottom thereof. The high velocity with which this oil is returned to the still through thenozzle 25 aids in the agitation of theoil, carbon, coke or tar in said still. The oil burners 18 at the various points of fuel consumption in the refinery are connected preferably to this high velocity circulating pipe line 17 and are thereby supplied with fuel. In the manner outlined above the mixture of oil, car bon, coke or tar is delivered to the burners at points of consumption. The temperatures and velocities are high enough to prevent clogging of the lines and burner apparatus. The lighter oil fractions which are vaporized or atomized in the still 13 rise to the top of the still and pass out through the vapor line 20 to a condenser coil 21 located, for example, in a water filled casing 22,

where these light oil fractions are condensed and cooled. This lighter oil then passes out of the condenser 21, through the pipe line 23 and into a storage tank 24. This recovered oil is valuable as cracking stock or oil that can be profitably put back through the cracking apparatus for further refinement or may be placed to any other purposes as a valuable product. The still 13 may be heated by a burner 30 if desired.

By the present invention it will be observed that a process is provided whereby the more valuable lighter oils are effectively extracted from the residuum products of cracking stills and distillation apparatus insuch manner as to avoid the waste and loss thereof and at the same time enabling the resulting extremely low grade products to be usefully employed, as in this instance, for fuel purposes. The process thus utilizes a product which has in most cases been greatly wasted by prior methods and has been handled only with great difliculty.

What is claimed is:

The process of treating petroleum residue obtained from cracking and distillatory apparatus, which consists in circulatin such residue through a conduit to a separating receptacle, in introducing an inert gas under pressure into said conduit so as to force said residue in an atomized finely divided forminto said receptacle, in maintaining the temperature and turbulence of said residue within the receptacle by the introduction of an additional quantity of a heated inert gas into said receptacle, withdrawing the lighter fractions of said residue from adjacent the top of said receptacle and transmitting the same to separate condensing and collecting apparatus, in continuously circulating hot residual oil through a closed ring, including said enlarged zone, and in supplying regulated quantities of hot residual oil from said ring to a plurality of burners positioned adjacent said ring, to constitute the fuel consumed in said burners, the major portion of the residual oil circulated through said ring being permanently removed therefrom.

In testimony whereof I aflix my signature.

CORNELIUS B. WATSON. 

